Research on the Evolvement of Ecological Environment in Songnen Plain with the Support of Multi-source Remote Sensing Information
|Keywords||Eco-environmental Change Quantitative Remote Sensing Land Use/Land Cover Change Desertification Assessment Ecological Assets Assessment Songnen Plain|
During the past half century, the global environment has changed dramatically, and oursociety is facing a series of major global environmental issues. Research on global change hasbecome the study hotspot which is a common concern of the international community. Theresearch on region’s ecological environment evolution is the base of global change research,but also is an important component of global change research Therefore, it has significance tocarry on the eco-environment change research in typical region.Songnen plain is one ofChina’s largest plain, but also an important national commodity grain base and the energyindustry base. The ecological environment deteriorated due to the dry warm unusual climate,excessive land reclamation, excessive herding and other human intense economic activity.The problems, which are the destruction of ecosystems, land degradation, desertification andgrassland degradation,became more serious. Regional ecological security was threatenedseriously, which constrains the coordinated development among social, economic andecological environmental. It is urgent to carry on multi-area and multi-level research oneco-environment in Songnen plain. The previous studies focused on the south-west inSongnen plain, and studies on the integrated geographical units were less. The studies usedsingle remote sensing data and the comprehensive application of multi-source remote sensingdata was less. The studies always paid attention to desertification and grassland degradation,and the ecological assets assessment research was rare. Therefore, it is necessary to makecomprehensive use of various theories and methods and adopt multi-source remote sensingdata and non-remote sensing data. The ecological environment changes of Songnen plainwere in the dynamic study from multi-time, multi-space and multi-scale.The author aimed at the eco-environment deterioration to carry on research in Songnenplain. Firstly, the characteristics and rules of eco-environmental changes were exposed in the11 years from 1989 to 2000 in Songnen plain hinterland from the LUCC changes, whichprovided rich microcosmic and quantitative information for eco-environment research.Secondly, the diagnostic index reflecting the eco-environment changes were inversed by usingMODIS data. On this basis, the multi-target desertification evaluation system was established.The author also did the dynamic monitoring on the state of desertification development from2002 to 2005. The ecological assets assessment study by using multi-source remote sensingtechnology in Songnen plain hinterland provided the basis for regional planning forsustainable development. Through researches on major eco-environment problems in Songnenplain, the author analyzed the eco-environmental change process. The cause, speed andcharacter of environmental degradation were revealed, and the eco-environment developmenttrend was forecasted. All this had great significance for management and restoration ofdegraded lands, protection and construction of regional ecological environment andachievement in region sustainable development.Land use/land cover is the most prominent visual symbol of earth surface system, whichrepresents the natural environment evolution and reflects the impact of human activities onthe ecological environment. The dynamic change of the land-use situation was as the studybase of the ecological environment changes. The author applied the RS-GIS integratedtechnology to get the land use maps of 1989 and 2000 in Songnen plains hinterland usingLandsat TM images. The land use change dynamics models, the land use degree models,structural characteristics models, regional relative rates of change models and the dynamictransformation models were applied to analyze and descript the land-use/land-coverquantitative dynamic in the whole region. Applied landscape ecology principles and methods,the author chose landscape indices to analyze the spatio-temporal processes of land-usechange and revealed the direction, characteristics and laws of ecological environmentchanges.The studies have shown that the reduction of grass, wetlands, waters and rapidly increasein saline alkali soil are the extrusive performance of the ecological environment deteriorationin Songnen plain hinterland. The paddy field was in a substantial increase and the woodlanddeclined in the northern hinterland. And in the southern hinterland the woodland increased,and saline alkali soils proliferated. The reduced area of wetlands in south is below the north,but because of its small base, as high as 3.27% of the degradation rate will deplete the wetlandresources. From the spatial distribution of changes, land-use change in north is more stronglythan in south and the northern land use situation is unstable. The overall trend of land usedegree is that east is higher than west, north is higher than south and plain is higher thanlowland. Land use structure change in southern hinterland is greater than the north, especiallygrassland degradation phenomenon is more serious than north. In a word, in the 11 years from1989 to 2000, land use changed dramatically in plain hinterland and land desertificationdegree aggravated. The heavy disaster areas of desertification were Tongyu, Daan, Changling,Dumeng and Daqing. The eco-environmental conditions were better in northern hinterlandthan in the south. From the perspective of land use change types, grassland resources turnedinto farmland, and saline alkali soil mainly came from the degradation of grasslands, watersand wetlands shrink. Grassland degradation and the increase of saline alkali land are the twomain change directions of the eco-environment in the study area. From the landscape indexchange, due to the human activities effects and the deterioration of the eco-environment, thepatches of grassland, dry land and wetlands turned into fragmentation trend. The boundaryshapes of patches turned into complication, irregularization and dispersed states. In contrast,the patches fragmentation of paddy fields and saline alkali soils decreased, and the boundaryshapes of patches turned into simplify regularization and a film focused direction.Land use change driving mechanism research plays an important role for revealing thecauses of the region eco-environment changes and predicting the future evolution trend. theauthor took the 10 cities and counties in the south-west of Songnen plain for example toanalyze quantitatively the interrelationship between driving factors and land use change usingtypical correlation analysis models to identify the major driving force of land use change.Research has shown that dry farmland increase and the organic matter content in soil waspositive correlation with the per capita income of farmer. And the saline alkali soils increasewas negative correlation with the per capita of water resource and the organic matter contentin soil, and was positive correlation with the population density. The thick grass decrease waspositive correlation with he population density and negative correlation with the per capita ofwater resource. The wetlands reduction was positive correlation with unit area andagricultural production and the population density. Population density, per capita waterresources and soil organic matter content were the three most important driven factorsaffecting LUCC changes. On the basis of driving factors analysis, the author simulateddynamically the spatial pattern change of land use by clue model in the south-westernSongnen plain. The distribution forecast of land use spatial pattern in 2010 has a referencevalue for governance and restoration of regional land degradation and the rational resourceexploitation.Underlying surface characteristic is the important factor affecting the exchange betweenground material and energy, but also is the important parameter reflecting the ecologicalevolution. MODIS remote sensing data has the characteristics, which are with high temporalresolution, spectral resolution, scope wide, low cost and multi-channel access. It has theobvious advantage to do quantitative research on the surface features changes in theecological environment. Based on the remote sensing theory and quantitative techniques, theauthor inversed the eco-environment parameters from MODIS high-spectral remote sensingdata in Songnen plain from 2002-2005, the period of four consecutive years. The parametersincluded normalized difference vegetation index, land surface temperature, soil moisture andvegetation net primary productivity. Through the analysis of the parameters from 2002 to2004, vegetation coverage dropped and land face temperature rose. The soil was arid andhumidity fell, and NPP also reduced. The ecological environment turns acidification, soilimpoverishment and quality degradation under the dry warming climate effects. As the highprecipitation in 2005, local regional ecological environment is improved, but theenvironmental deterioration trend has not changed in the whole Songnen plain.Sandy desertification and alkali desertification are the most prominent ecologicalenvironment problems in Songnen plain. Those are the important research contents oneco-environment change to understand the spatial distribution laws of land desertification, tomaster desertification trends and to evaluate the land desertification extent. On the basis of thepredecessor’s research, based on the high-spectral remote sensing technology, the authorestablished the evaluation index system which included the vegetation coverage, improvedsoil-vegetation index, vegetation net primary productivity, land surface temperature and soilmoisture. On the basis of index acquired from the MODIS data, the author use gray relevancedegree model to evaluate the desertification for four consecutive years 2002-2005 in Songnenplain. The results showed that the area of desertification has increased and the extent ofdesertification has aggravated between 2002 and 2004 in Songnen plain. The precipitationincrease decreased the desertification area slightly in 2005, but the overall trend is continuingdeterioration. The desertification mainly distributed in the western plain hinterland. Thedesertification in Daan, Tongyu, Dumeng and Daqing was the most serious. Contrast to thesimilar researches, such evaluation could do land desertification assessment continuously andrapidly. The multiple indicator evaluation system can reflect the land desertificationcharacteristics from multi-point of view, and it can conquer error from single indicatorevaluation. The evaluation results have certain precision so the system has promoted value.Ecological assets are the key content and focus for assessment on region sustainabledevelopment, but also are the important gist to measure the regional eco-environmentalconditions. This thesis based on multi-scale remote sensing data to pick up the ecologicalenvironment quantitative parameters. The ecological assets were assessed in Songnen plainhinterland applying ecological assets value models, and the spatial distribution patterns wereanalyzed. The results showed that sandy plain hinterland overall of the, the contribution ratioof dry farmland was the largest in ecological assets value in Songnen plain. The second werewoodland and wetlands. The average ecological assets value of woodlands, wetlands andthick grass were higher. So to strengthen the cropland conversion to forest and grassland, andto protect and resume wetlands were the important part for eco-environment constructionBecause of serious land degradation and desertification, the average ecological assets value ofTongyu, Daan, Daqing, Changling, Taonan, Daqing and Dumeng were low. The landdesertification has become a major factor constraining the region sustainable development.The features and innovations of the thesis were that the eco-environmental changes werecarried on from the multi-angle and multi-scale using multi-source remote sensing data andintegrated multidisciplinary theory and methods. The eco-environment study breadth anddepth were expanded. This is an attempt and exploration for study on regionaleco-environment, which has some certain theoretical significance and applied reference value.In addition, the author used the integrated LUCC dynamics models and landscape patternanalysis methods to analyze the dynamics land-use/land-cover change qualitatively andquantitatively for 11 years in Songnen plain hinterland. From the microcosmic perspective,the author revealed the time and space process of the eco-environment change, and analyzedthe different characteristics of the eco-environment evolution in the southern and northernplain hinterland. The author analyzed the driving mechanism of LUCC quantitatively usingtypical related models and simulated the spatial pattern using clue model for first time.In addition, the author applied multi-source remote sensing data to do some exploratorywork on eco-environment quantitative research. The land surface temperature, soil moistureand NPP were inversed quantitatively by MODIS high-spectral remote sensing data, andmulti-index desertification evaluation system was established according to the fact in Songnenplain for first time. Regional sustainable development evaluation in Songnen plain was carriedon using the theory and methods of ecological asset for first time.